The acute effect of insulin on renal haemodynamics and protein excretion in diabetics.

The effect of IV injection of 7 to 8 I. U. of insulin on renal haemodynamics and on urinary excretion of beta-2-microglobulin and of albumin was examined in 5 juvenile diabetics. Plasma glucose decreased from a mean value of 250 mg/100 ml to 117 mg/100 ml during the first 85 min after insulin. None of the patients had symptoms of hypoglycaemia and plasma adrenaline did not increase. There was no change in arterial blood pressure after insulin whereas pulse rate increased from 66/min to a maximum of 75/min. Glomerular filtration rate (GFR) and renal plasma flow (RPF) were decreased by 9 per cent and 13 per cent, respectively, during the first 90 min after insulin (2 p less than 0.01). There was also a statistically significant decrease in urine flow and urine secretion of several electrolytes, while filtration fraction remained almost constant. IV insulin decreased urinary excretion of beta-2-microglobulin and increased albumin excretion (2 p less than 0.05). The albumin excretion induced by insulin is most likely due to increased amounts of filtered albumin, the mechanism of which remains unexplained.